Near-field transducer peg encapsulation

ABSTRACT

A near field transducer with a peg region, an enlarged region disposed adjacent the peg region, and a barrier material disposed between the peg region and the enlarged region. The barrier material reduces or eliminates interdiffusion of material between the peg region and the enlarged region.

SUMMARY

Embodiments disclosed include a near field transducer with a peg region,an enlarged region disposed adjacent the peg region, and a barriermaterial disposed between the peg region and the enlarged region. Thebarrier material reduces or eliminates interdiffusion of materialbetween the peg region and the enlarged region.

Embodiments are directed to a system for a heat assisted magneticrecording head that includes a near field transducer having a pegregion, an enlarged region, and a barrier material. The barrier materialis disposed between the peg region and the enlarged region to reduceinterdiffusion of material between the peg region and the enlargedregion.

Further embodiments are directed to a method of fabricating a near fieldtransducer for a heat assisted magnetic recording head including forminga peg region along a substrate of a heat assisted magnetic recordinghead, disposing a sacrificial material over a first portion of the pegregion leaving a second portion of the peg region exposed, fabricating abarrier material over at least the second portion of the peg region,forming an enlarged region adjacent the second portion of the peg regionsuch that the barrier material is disposed at least between the secondportion and the enlarged region to reduce interdiffusion between the pegregion and the enlarged region, and removing the sacrificial material.

The above summary is not intended to describe each disclosed embodimentor every implementation of the present disclosure. The figures and thedetailed description below more particularly exemplify illustrativeembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Throughout the specification reference is made to the appended drawings,where like reference numerals designate like elements, and wherein:

FIG. 1 is a perspective view of a hard drive slider that includes adisclosed near-field transducer;

FIG. 2 is a side cross-sectional view of an apparatus that includes thenear-field transducer of FIG. 1, a write pole, a heat sink, and awaveguide according to an example embodiment;

FIG. 3 is a first cross-sectional view of one embodiment of a near-fieldtransducer that includes a peg region separated from an enlarged regionby a barrier material;

FIG. 3A is a second cross-sectional view of the near-field transducer ofFIG. 3;

FIG. 4 is side cross-sectional view of another embodiment of anear-field transducer that includes a peg region separated from anenlarged region by a barrier material;

FIG. 4A is a second cross-sectional view of the near-field transducer ofFIG. 4;

FIG. 5 is a cross-sectional view of another embodiment of a near-fieldtransducer with a spacing element and a peg region of the near-fieldtransducer separated from one another;

FIG. 5A is a second cross-sectional view of the near-field transducerand spacing element of FIG. 5; and

FIG. 6 is an illustration of one step in various fabrication techniquesused to form a near-field transducer.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying setof drawings that form a part of the description hereof and in which areshown by way of illustration several specific embodiments. It is to beunderstood that other embodiments are contemplated and may be madewithout departing from the scope of the present disclosure. Thefollowing detailed description, therefore, is not to be taken in alimiting sense.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein. The use of numerical ranges by endpointsincludes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, and 5) and any range within that range.

Various embodiments disclosed herein are generally directed to systemsand apparatuses that facilitate coupling a laser diode to a magneticwriter that includes a magnetic write head. In particular, the systemsand apparatuses include a plasmonic near-field transducer for heatassisted magnetic recording (HAMR). Plasmonic near-field transducers(NFTs) can generate a large amount of heat in their writing tip alsocalled a “peg” or “peg region”. This heat can negatively impact theoperational life of the near-field transducer. Disclosed areapparatuses, systems, and methods directed to increasing NFT operationallife by reducing likelihood of peg recession of the writing tip. Inparticular, disclosed herein are systems, apparatuses, and methods thatseparate a peg region from the remainder of the NFT by a barriermaterial. This encapsulation of the peg region (writing tip) from theremainder of the NFT reduces or eliminates interdiffusion of materialbetween the peg region and the remainder of the NFT. The reduction orelimination of interdiffusion of material reduces the likelihood of pegrecession. Thus, the near-field transducer can better withstand heatbuildup in the peg for HAMR.

The present disclosure relates to HAMR, which can be used to increaseareal data density of magnetic media. In a HAMR device, information bitsare recorded in a storage layer at elevated temperatures in a speciallyconfigured magnetic media. The use of heat can overcomesuperparamagnetic effects that might otherwise limit the areal datadensity of the media. As such, HAMR devices may include magnetic writeheads for delivering electromagnetic energy to heat a small confinedmedia area (spot size) at the same time the magnetic write head appliesa magnetic field to the media for recording.

One way to achieve a tiny confined hot spot is to use an opticalnear-field transducer (NFT), such as a plasmonic optical antenna or anaperture, located near an air-bearing surface of a hard drive slider.Light may be launched from a light source (e.g., a laser diode) intooptics such as a waveguide integrated into the slider. Light propagatingin the waveguide may be directed to an optical focusing element, such asa planar solid immersion mirror (PSIM). The PSIM may concentrate theenergy into a NFT. The NFT causes the energy to be delivered to themedia in a very small spot.

FIG. 1 is a perspective view of a hard drive slider that includes adisclosed plasmonic NFT. HAMR slider 100 includes laser diode 102located on top of HAMR slider 100 proximate to trailing edge surface 104of HAMR slider 100. Laser diode 102 delivers light proximate toread/write head 106, which has one edge on air-bearing surface 108 (alsoreferred to as “media-facing surface” or “media interfacing surface”) ofHAMR slider 100. Air-bearing surface 108 is held proximate to a movingmedia surface (not shown) during device operation.

Laser diode 102 provides electromagnetic energy to heat the media at apoint near to read/write head 106. Optical coupling components, such asa waveguide 110, are formed integrally within HAMR slider 100 to deliverlight from laser diode 102 to the media. In particular, waveguide 110and NFT 112 may be located proximate read/write head 106 to providelocal heating of the media during write operations. Laser diode 102 inthis example may be an integral, edge-emitting device, although it willbe appreciated that waveguide 110 and NFT 112 may be used with any lightsource and light delivery mechanisms. For example, a surface emittinglaser (SEL) may be used instead of the edge firing laser illustrated.

While the example in FIG. 1 shows laser diode 102 integrated with HAMRslider 100, the NFT 112 discussed herein may be useful in any type oflight delivery configuration. For example, in a free-space lightdelivery configuration, a laser may be mounted externally to the slider,and coupled to the slider by way of optic fibers and/or waveguides. Theslider in such an arrangement may include a grating coupler into whichlight is coupled and delivered to slider-integrated waveguide 110 whichenergizes the NFT 112.

The HAMR device utilizes the types of optical devices described above toheat he magnetic recording media (e.g., hard disc) in order to overcomethe superparamagnetic effects that limit the areal data density oftypical magnetic media. When writing to a HAMR medium, the light can beconcentrated into a small hotspot over the track where writing takesplace. The light propagates through waveguide 110 where it is coupled tothe NFT 112 either directly from the waveguide or by way of a focusingelement. Other optical elements, such as couplers, mirrors, prisms,etc., may also be formed integral to the slider. The optical elementsused in HAMR recording heads are generally referred to as integratedoptics devices.

As a result of what is known as the diffraction limit, opticalcomponents cannot be used to focus light to a dimension that is lessthan about half the wavelength of the light. The lasers used in someHAMR designs produce light with wavelengths on the order of 700-1550 nm,yet the desired hot spot is on the order of 50 nm or less. Thus thedesired hot spot size is well below half the wavelength of the light.Optical focusers cannot be used to obtain the desired hot spot size,being diffraction limited at this scale. As a result, the NFT 112 isemployed to create a hotspot on the media.

The NFT 112 is a near-field optics device designed to reach localsurface plasmon resonance at a designed wavelength. A waveguide and/orother optical element concentrates light on a transducer region (e.g.,focal point) where the NFT 112 is located. The NFT 112 is designed toachieve surface plasmon resonance in response to this concentration oflight. At resonance, a high electric field surrounds the NFT 112 due tothe collective oscillations of electrons at the metal surface. Part ofthis field will tunnel into a storage medium and get absorbed, therebyraising the temperature of a spot on the media as it being recorded.NFTs generally have a surface that is made of a material that supportssurface plasmons (“plasmonic metal”) such as aluminum, gold, silver,copper, or alloys thereof. They may also have other materials but theymust have a material that supports surface plasmons on their outersurface.

FIG. 2 is a cross-sectional view shows details of an apparatus 200 usedfor HAMR according to an example embodiment. The NFT 112 is locatedproximate a media interfacing surface 202 (e.g., ABS), which is heldnear a magnetic recording media 204 during device operation. In theorientation of FIG. 2, the media interfacing surface 202 is arrangedparallel to the x-z plane. A waveguide 206 may be disposed proximate theNFT 112, which is located at or near the media writing surface 214.

The NFT 112, waveguide 206, and other components are built on asubstrate plane, which is parallel to the x-y plane in this view.Waveguide 206 is shown configured as a planar waveguide, and issurrounded by cladding layers (not shown) that have different indices ofrefraction than a core of the waveguide 206. Other waveguideconfigurations may be used instead of a planar waveguide, e.g., channelwaveguide. Light propagates through the waveguide 206. Electrical fieldlines emanate from the waveguide 206 and excite the NFT 112. The NFT 112delivers surface plasmon-enhanced, near-field electromagnetic energyalong the negative y-direction where it exits at the media interfacingsurface 202. This may result in a highly localized hot spot (not shown)on the magnetic recording media 204. A magnetic recording pole 215 thatis located alongside NFT 112. The magnetic recording pole 215 generatesa magnetic field (e.g., perpendicular field) used in changing themagnetic orientation of the hotspot during writing.

Many NFT designs include an enlarged region as well a peg region. Theenlarged region will typically comprise substantially 90% or more of thevolume of the NFT in some embodiments. Although discussed as a separateregion or portion, typically the peg region is integrally fabricated ofa same material as the enlarged region. The specific wavelength of lightfrom the laser diode dictates the size of the enlarged region of the NFTand a length of the peg region in order to get optimal (maximum)coupling efficiency of the laser light to the NFT.

As discussed previously, the peg region acts as the writing tip of theNFT while the enlarged region is configured to receive concentratedlight from the laser diode/waveguide and is designed to help NFT achievesurface plasmon resonance in response to this concentration of light.The peg region is in optical and/or electrical communication with theenlarged region and creates a focal point for the energy received by theenlarged region.

As is known, temperature increases in the peg region are a challenge forthe durability of HAMR devices. A temperature mismatch between therelatively higher temperature peg region and relatively lowertemperature enlarged region as well as mechanical stresses are thoughtto lead to an exchange of material (and vacancies) between the tworegions. As used herein, the term “material” additionally includes anyvacancies within the material. The temperature mismatch between the tworegions as wells as the mechanical stresses are thought to be phenomenonthat drive peg deformation and peg recession, which can lead to failureof the HAMR device.

The present disclosure relates to apparatuses, systems, and methodsrelated to an NFT for the HAMR device. In particular, embodiments of theNFT include a peg region that is separated from the remainder of the NFTby a barrier material. This encapsulation of the peg region from theremainder of the NFT reduces or eliminates interdiffusion of materialbetween the peg region and the remainder of the NFT. The reduction orelimination of interdiffusion of material reduces the likelihood of pegrecession and failure of the HAMR device.

FIG. 3 shows a cross-sectional view of one embodiment of an NFT 312.FIG. 3A is a second cross-sectional view of the NFT 312. As illustratedin FIGS. 3 and 3B, the NFT 312 includes a peg region 302, an enlargedregion 304, and a barrier material 306. Additionally, the peg region 302includes surfaces 308 a, 308 b, 308 c, and 308 d and the enlarged region304 includes arcuate surface 310 and bottom surface 314.

The enlarged region 304 is disposed adjacent the peg region 302. Thebarrier material 306 is disposed between the peg region 302 and theenlarged region 304 to reduce or eliminate interdiffusion of materialsbetween the peg region 302 and the enlarged region 304. However, the pegregion 302 remains in optical and/or electrical communication with theenlarged region 304.

The peg region 302 can extend from the enlarged region 304 towardmedia-facing surface (e.g., media interfacing surface 202 in FIG. 2). Inthe illustrated embodiment, the enlarged region 304 has a circular diskshape. In the context of describing the shape of the enlarged region304, the term “disk” refers to three-dimensional shapes that include acylindrical or tapered cylindrical portion, a bottom surface 314, and atop surface. Thus, the disk shape can include a truncated conical shapein some instances. The bottom surface 314 may or may not be arranged ina plane parallel with the top surface. The peg region 302 and theenlarged region 304 can be formed from a thin film of plasmonic metal(e.g., aluminum, gold, silver, copper, and combinations or alloysthereof) on a substrate plane of the slider proximate the write pole(e.g., magnetic recording pole 215 in FIG. 2). In some embodiments, thepeg region 302 and the enlarged region 304 can be formed from the samematerial.

The barrier material 306 is disposed between the peg region 302 and theenlarged region 304, and in particular, is arranged to substantiallyseparate (encapsulate) the peg region 302 from the enlarged region 304.As illustrated in FIGS. 3 and 3A, the barrier material 306 can bedisposed on a portion of the peg region 302 opposing the surface 308 a(i.e., a non-media interfacing end of the peg region 302). The length,thickness, and other dimensional and physical properties of the barriermaterial 306 will depend upon the composition of the peg region andenlarged region and upon the specific wavelength of light from the laserdiode. In one embodiment the barrier material 306 has a thickness ofbetween about 1.0 nm and about 10.0 nm.

As illustrated, the barrier material 306 disposed along a side of thepeg region 302 can have thicknesses t₁ that differ from a thickness t₂of the barrier material 306 disposed along a top of the peg region 302and/or a thickness t₃ of the barrier material 306 disposed along anon-media interfacing back of the peg region 302. The barrier material306 can be comprised of one or more of ZrN, TiN, Rh, Zr, Hf, Ru, AuN,TaN, Ir, W, Mo, Co, and alloys thereof. It is desirable that barriermaterial 306 create a diffusion barrier for Au and other plasmonicmetals and have a thermal conductivity greater than about 10 W/m-K insome embodiments. It is also desirable in some instances that barriermaterial 306 has appreciable optical figure of merit. Although bestdescribed as a layer in some embodiments, barrier material 306 caninclude one or more layers or can be a component that is not layered innature in some instances.

As shown in FIGS. 3 and 3A, the barrier material 306 encapsulates thepeg region 302 by extending between the arcuate surface 310 and thebottom surface 314 of enlarged region 304. In the embodimentillustrated, the barrier material 306 extends along a plane thatsubstantially aligns with surfaces 308 b, 308 c, and 308 d of the pegregion 302. However, in other embodiments the barrier material 306 maynot substantially align with surfaces 308 b, 308 c, and 308 d. As willbe discussed subsequently, the barrier material 306 is fabricated to beself-aligned using electro-deposition, plasma treatment/annealing,dopant/annealing, and/or plasma treatment/electrochemical processingetc. The self-aligned fabrication methods allow the barrier material 306to be disposed substantially only between the peg region 302 and theenlarged region 304 according to various embodiments.

FIGS. 4 and 4A show another embodiment of an NFT 412 fabricated usingnon-self-aligned methods. FIG. 4 shows a first cross-sectional view ofthe NFT 412. FIG. 4A is a second cross-sectional view of the NFT 412. Asillustrated in FIGS. 4 and 4B, the NFT 412 includes a peg region 402, anenlarged region 404, and a barrier material 406. Additionally, the pegregion 402 includes surfaces 408 a, 408 b, 408 c, and 408 d and theenlarged region 404 includes an arcuate surface 410 and bottom surface414.

The general characteristics of the NFT 412 have been previouslydescribed in reference to the NFT 312 of FIGS. 3 and 3A, and, therefore,will not be described in great detail. However, the embodiment of FIGS.4 and 4A differs from that of FIGS. 3 and 3A in that the barriermaterial 406 is disposed between the enlarged region 404 and the pegregion 402 and is additionally disposed along the arcuate surface 410and the bottom surface 414 of the enlarged region 404. In FIGS. 4 and4A, the barrier material 406 is fabricated to be non-self-aligned usingknown lithography methods, e.g. sputtering. The non-self-alignedfabrication methods allow the barrier material 406 to be disposedbetween the enlarged region 404 and the peg region 402 and along one ormore additional surfaces of the enlarged region 404.

FIG. 5 shows a cross-sectional view of another embodiment of an NFT 512and a spacing element 516. FIG. 5A is a second cross-sectional view ofthe NFT 512 and the spacing element 516. As illustrated in FIGS. 5 and5A, the NFT 512 includes a peg region 502, an enlarged region 504, and abarrier material 506. Additionally, the peg region 502 includes surface508 a and the enlarged region 504 includes arcuate surface 510 andbottom surface 514.

The general characteristics of the NFT 512 have been previouslydescribed in reference to the NFT 512 of FIGS. 5 and 5A, and, therefore,will not be described in great detail. However, the embodiment of FIGS.5 and 5A differs from that of FIGS. 3 and 3A in that the barriermaterial 506 is disposed between enlarged region 504 and peg region 502and is additionally disposed between the NFT 512 and the spacing element516. The spacing element 516 is disposed to interface with the pegregion 502 and extends between the enlarged region 504 and a pole (e.g.,the magnetic recording pole 215 of FIG. 2). In the illustratedembodiment, the spacing element 516 is dispose around several sidesurfaces (e.g., surfaces 308 a, 308 b, and 308 c in FIGS. 3 and 3A) butdoes not contact peg region 502 as barrier material 506 is disposedtherebetween. Thus, only the surface 508 a, as well as a bottom surfaceof the peg region 502 are not encapsulated by the barrier material 506.The spacing element 516, also called a NFT to pole spacing (“NPS”), canbe formed by a deposition process in some instances, and can becomprised of an electrically insulating material. It is also desirablein some instances that spacing element 516 has appreciable opticalfigure of merit.

FIG. 6 illustrates a one step in a method of fabricating an NFT. Asillustrated in FIG. 6, the peg region 602 is formed using knownlithography methods prior to formation of the enlarged region. Asacrificial material 620, such as a photoresist, is disposed over afirst portion 622 of the peg region 602, leaving a second portion 624 ofthe peg region 602 exposed. A barrier material 606 is fabricated overthe second portion 624 of the peg region 602.

In one embodiment, the barrier material 606 is fabricated using a vacuumdeposition (dc/rf/reactive sputtering, ion beam deposition, evaporation)or an electroplating process that disposes a metal such as Rh, Zr, Hf,Ru, Ir, W, Mo, Co and alloys thereof over one or more surfaces of thesecond portion 624. In another embodiment, the barrier material 606 isfabricated by applying a nitride forming compound such as Zr, Ti, Au,Ta, W in low concentrations, i.e., <1 by weight %. In some embodiments,nitrides formed with the disclosed compounds act as an effectivediffusion barrier when they form stoichiometric nitrides having thelowest achievable resistivity and highest achievable optical figure ofmerit to the peg region 602. The nitride forming compound can be appliedas a diffuse dopant or as a layer in the formation of the peg region602. The exposed second portion 624 containing the nitride formingcompound can be annealed in nitrogen or nitrogen plasma at or relativelynear atmospheric pressure at a temperature between about 100° C. andabout 400° C. for a duration of up to several hours. The annealingprocess causes the nitride forming compound to form nitrides such asZrN, TiN, AuN, TaN, WN along the one or more surfaces of the secondportion 624 (i.e., the surfaces exposed to the nitrogen or nitrogenplasma). In yet another embodiment, the barrier material 606 can becomprised of AuN and is fabricated by annealing the exposed secondportion 624 of the peg region 602 in nitrogen or nitrogen plasma at orrelatively near atmospheric pressure at a temperature between about 100°C. and about 400° C. for a duration of up to several hours. In anotherembodiment, the barrier material 606 can be comprised of AuO and isfabricated either electrochemically or by annealing the exposed secondportion 624 of the peg region 602 in oxygen or oxygen plasma at orrelatively near atmospheric pressure at a temperature between about 100°C. and about 400° C. for a duration of up to several hours.

The enlarged region (e.g., the enlarged region 304 of FIGS. 3, 3A) isformed between the portions of the sacrificial material 620. Thus, theenlarged region is disposed adjacent and along the second portion 624 ofthe peg region 602 such that the barrier material 606 is disposed atleast between the second portion 624 and the enlarged region (not shownin FIG. 6) to reduce interdiffusion between the peg region 602 and theenlarged region. After formation of the enlarged region 604, thesacrificial material 620 can be removed using lithography processes suchas ion milling and other techniques.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations can besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present disclosure. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisdisclosure be limited only by the claims and the equivalents thereof.All references cited within are herein incorporated by reference intheir entirety.

What is claimed is:
 1. An apparatus, comprising: a near field transducercomprising a peg region and an enlarged region disposed adjacent the pegregion; and a barrier material disposed between the peg region and theenlarged region configured to reduce interdiffusion between the pegregion and the enlarged region.
 2. The apparatus of claim 1, wherein thepeg region comprises a plasmonic metal.
 3. The apparatus of claim 2,wherein the enlarged region comprises a second plasmonic metal that hasa same composition as the plasmonic metal of the peg region.
 4. Theapparatus of claim 1, wherein the barrier material comprises one or moreof ZrN, ZrN, TiN, Rh, Zr, Hf, Ru, AuN, TaN, Ir, W, Mo, Co, and alloysthereof.
 5. The apparatus of claim 1, wherein the barrier materialcomprises one or more layers that substantially separate the peg regionfrom the enlarged region.
 6. The apparatus claim 1, wherein the barriermaterial extends along a non-media interfacing end of the peg region. 7.The apparatus of claim 1, wherein the barrier material has a thicknessof between about 1.0 nm and about 10.0 nm.
 8. The apparatus of claim 1,wherein the barrier material is disposed only between the enlargedregion and the peg region.
 9. The apparatus of claim 1, wherein thebarrier material is disposed between the enlarged region and the pegregion and along one or more additional surfaces of the enlarged region.10. The apparatus of claim 1, wherein the enlarged region is a diskshaped object.
 11. An apparatus, comprising: a system configured tofacilitate heat assisted magnetic recording; and a near field transducerdisposed in the system, the near field transducer comprising: a pegregion and an enlarged region; and a barrier material disposed betweenthe peg region and the enlarged region configured to reduceinterdiffusion between the peg region and the enlarged region.
 12. Thesystem of claim 11, wherein the enlarged region comprises a secondplasmonic material that has a same composition as a first plasmonicmaterial of the peg region.
 13. The system of claim 11, wherein thebarrier material comprises one or more of ZrN, TiN, Rh, Zr, Hf, Ru, AuN,TaN, Ir, W, Mo, Co, and alloys thereof.
 14. The system of claim 11,wherein the barrier material has a thickness of between about 1.0 nm andabout 10.0 nm.
 15. The system of claim 11, wherein the barrier materialis disposed only between the enlarged region and the peg region.
 16. Thesystem of claim 11, wherein the barrier material is disposed between theenlarged region and the peg region and along one or more additionalsurfaces of the enlarged region.
 17. A method, comprising: forming a pegregion of a near field transducer along a substrate of a heat assistedmagnetic recording head; disposing a sacrificial material over a firstportion of the peg region leaving a second portion of the peg regionexposed; fabricating a barrier material over at least the second portionof the peg region; forming an enlarged region adjacent the secondportion of the peg region such that the barrier material is disposed atleast between the second portion and the enlarged region to reduceinterdiffusion between the peg region and the enlarged region; andremoving the sacrificial material.
 18. The method of claim 17, whereinthe step of fabricating includes annealing the second portion.
 19. Themethod of claim 18, wherein the step of annealing comprises contactingthe second portion with one or more of nitrogen, nitrogen plasma,oxygen, and oxygen plasma.
 20. The method of claim 17, wherein the stepof fabricating the barrier material comprises electroplating one or moresurfaces of the second portion.